The Global System for Mobile (GSM) communication system used in wireless telecommunications employs a time-division multiple access (TDMA) scheme. Such a system allows multiple users to share a same frequency channel by dividing the channel into different timeslots. Each timeslot, also referred to as a “slot” in the present disclosure, provides an available transmission time for a participant on the system. Thus, the participants transmit to and receive from a network in succession within their assigned timeslots.
For GSM, each system frequency is divided into eight timeslots collectively referred to as a frame or a TDMA frame. These timeslots and frames repeat in time and provide a framework for communications in both the uplink (from a mobile station or user equipment to a base station or network) and the downlink (from the base station or network to the mobile station or user equipment).
Developing universally-accepted telecommunication standards has been a goal at the forefront of the Third Generation Partnership Project (3GPP). One such development in recent years is the GSM/EDGE radio access network (GERAN) standard. Among many things, 3GPP GERAN dictates that a mobile station has a multislot class that determines the maximum number of timeslots the mobile station can use for transmission and reception within any given TDMA frame, and hence the maximum bandwidth that can be allocated to the mobile station in the uplink and downlink directions.
In different situations, the bandwidth needs of one direction may be far greater than in the other direction. In addition, the bandwidth needs in the uplink and the downlink may be subject to significant and recurrent variations, requiring flexible adjustment of timeslot assignments and allocation. Flexible Timeslot Assignment (FTA) and Enhanced Flexible Timeslot Assignment (EFTA) are features of GERAN respectively introduced in 3GPP GERAN Release 7 and Release 9. Both FTA and EFTA features address the need to permit greater flexibility with respect to bandwidth allocations between the uplink and the downlink.